spring-2017

Modern plate tectonics on Earth is characterized by rigid plate motion at a global scale associated with recycling of its outer thermal boundary layer. During the early Earth, primitive plate tectonics may operate that could have been expressed by recycling of the thermal boundary layer without rigid plate motion similar to the inferred processes on Venus and Enceladus, or plate tectonics active only at a local scale as inferred on Mars and Europa. The local plate tectonics scenario would permit alternative modes of tectonic processes such as plume, drip, sag, stagnant-lid, and heat-pipe, and lower-crustal delamination to have occurred simultaneously on early Earth. This simple conceptual framework reconciles diverse and seemingly incompatible observations on early Earth that indicates various geologic processes in consistent with a unified global plate tectonics. In this talk, I will use the geology of the 2.0 Ga Limpopo belt and 3.5-3.2 Ga Barberton tectonic domain in South Africa to test whether primitive plate tectonics or other forms of tectonic processes may have been responsible for their formation.